GFA protein is the subunit of glio-specific filaments and a major product of astroglial differentiation. GFA protein is of particular interest for studies of the astroglial response to injury characterized by the accumulation of cytoplasmic filaments (fibrous gliosis). The study proposes: i, to conduct comparative biochemical, biophysical and immunological investigations of GFA protein and other intermediate filament proteins also present in astroglia; ii, to study turnover of GFA protein in vivo and in vitro; iiim to conduct experiments aimed at characterizing cytoskeletal transitions during differentiation in vivo and in vitro and following brain injury; iv, to conduct detailed morphological studies of glio-axonal interactions in CNS regeneration induced by peripheral nerve implants. Finally, the specificity of GFA protein for astroglia will be re-assessed following a recent report describing the presence of GFA protein in Schwann cells (peripheral glia). It is hoped that these studies will lead to a greater understanding of the role of neuroglia in neurological diseases.